To evaluate the clinical diagnostic efficacy of accelerated 3D magnetic resonance (MR) neuroimaging by radiological assessment for image quality and artefacts.
Prospective healthy volunteer study.
Eight healthy subjects.
Inversion Recovery (IR) prepared 3D Gradient Echo (GRE) sequence on a 1.5T GE Signa HDx scanner.
Independent radiological diagnostic quality assessments of accelerated 3D MR brain datasets were carried out by four experienced neuro-radiologists who were blinded to the acceleration factor and to the subject. The radiological grading was based on a previously reported radiological scoring key that was used for image quality assessment of human brains.
Bland-Altman analysis.
Optimization of the k-space sampling order was important for preserving contrast in accelerated scans. Despite having lower scores than fully sampled datasets, the majority of the compressed sensing (CS) accelerated brain datasets with k-space sampling order optimization (19/24 datasets by Radiologist 1, 24/24 datasets by Radiologist 2 and 16/24 datasets by Radiologist 3) were graded to be fully diagnostic indicating that there was adequate confidence for performing gross structural assessment of the brain.
Optimization of k-space acquisition order improves the clinical utility of CS accelerated 3D neuroimaging. This method may be appropriate for routine radiological assessment of the brain.
Optimization of k-space acquisition order improves the clinical utility of CS accelerated 3D neuroimaging. This method may be appropriate for routine radiological assessment of the brain.Individual channel ultra-high field (7T) phase images have to be phase offset corrected prior to the mapping of magnetic susceptibility of tissue. Whilst numerous methods have been proposed for gradient recalled echo MRI phase offset correction, it remains unclear how they affect quantitative magnetic susceptibility values derived from phase images. Methods already proposed either employ a single or multiple echo time MRI data. In terms of the latter, offsets can be derived using an ultra-short echo time acquisition, or by estimating the offset based on two echo points with the assumption of linear phase evolution with echo time. Our evaluation involved 32 channel multi-echo time 7T GRE (Gradient Recalled Echo) and ultra-short echo time PETRA (Pointwise Encoding Time Reduction with Radial Acquisition) MRI data collected for a susceptibility phantom and three human brains. The combined phase images generated using four established offset correction methods (two single and two multiple echo time) were analysed, followed by an assessment of quantitative susceptibility values obtained for a phantom and human brains. The effectiveness of each method in removing the offsets was shown to reduce with increased echo time, decreased signal intensity and reduced overlap in coil sensitivity profiles. Quantitative susceptibility values and how they change with echo time were found to be method specific. Phase offset correction methods based on single echo time data have a tendency to produce more accurate and less noisy quantitative susceptibility maps in comparison with methods employing multiple echo time data.There is a clinical interest in identifying normal appearing white matter (NAWM) areas in brain T2-weighted (TW) MRI scans in multiple sclerosis (MS) subjects. These areas are susceptible to disease development and areas need to be studied in order to find potential associations between texture feature changes and disease progression.
The subjects investigated had a first demyelinating event (Clinically Isolated Syndrome-CIS) at baseline (Time), and the NAWM(i.e. https://www.selleckchem.com/products/mi-773-sar405838.html NAWM at Time) of the brain tissue was subsequently converted to demyelinating plaques (as evaluated in a follow up MRI at Time). 38 untreated subjects that had developed a CIS, had brain MRI scans within an interval of 6-12months (Timeat follow-up). An experienced MS neurologist manually delineated the demyelinating lesions at Time(L) and at Time(L). Areas in the TimeMRI scans, where new lesions had been developed, were mapped back to their corresponding NAWM areas on the TimeMR scans (ROIS). In addition, contralateral ROIs of similar size and shape were segmented on the same images at Time(ROIS) to form an intra-subject control group. Following that, texture features were extracted from all prescribed areas and MS lesions.
Texture features were used as input into Support Vector Machine (SVM) models to differentiate between the following NAWMvs ROIS, NAWMvs NAWM, NAWMvs L, NAWMvs L, ROISvs L, ROISvs Land ROISvs ROIS, where the corresponding % correct classifications scores were 89%, 95%, 98%, 92%, 85%, 90% and 65% respectively.
Texture features may provide complementary information for following up the development and progression of MS disease. Future work will investigate the proposed method on more subjects.
Texture features may provide complementary information for following up the development and progression of MS disease. Future work will investigate the proposed method on more subjects.To compare the imaging characteristics of the volumetric-interpolated breath-hold examination (VIBE) using compressed-sensing (CS) acceleration (CS-VIBE) with the conventional sequence relying on parallel imaging to assess the potential use of CS-VIBE as a functional imaging technique for upper abdominal haemodynamics.
Patients (30 men, 27 women) suspected of having a hepatic disease underwent magnetic resonance imaging (MRI) of the liver, including a dynamic contrast-enhanced study. Gadolinium-ethoxybenzyl-diethylenetriamine pentaacetic acid was used as the contrast agent. MRI data of two multi-phase breath-hold exams were used for intra-individual comparisons. The VIBE and CS-VIBE were performed on different days. Image quality in both sequences was qualitatively assessed by three experienced radiologists. Moreover, the contrast ratio (CR) of the aorta, portal vein, liver and pancreas to muscle tissue were measured as a quantitative assessment. For the CS-VIBE, a five-phase time-intensity curve (TIC) was created to evaluate haemodynamics.